Ware Opening is an uncommon chess opening in which White opens with 1.a4 (see algebraic notation). It is named after U.S. chess player Preston Ware (1821–1891), who often played uncommon openings.

Ware opening attacks the b5 square and threatens to bring the a1 rook to the game. Practically it is one of the worst moves White can play. The b5 square is non-essential and if Black plays 1..e5, the f8 bishop prevents developing the white rook. 1..e5 also gains space for Black in the center, something that openings are supposed to do but Ware Opening fails in. Noting all this, the Ware Opening is something one could only expect to see from players completely new to chess.

1.a4 e5 2.h4 is called the Ware Opening / Crab variation. It does not bring any extra value for White but rather weakens his position even more. However, it is possible that after a few moves Ware Opening transposes to some other opening, like the Slav Defense.